1. Field of the Invention
The present invention relates to an apparatus and a method used to compress image data. More particularly, the present invention relates to a method of increasing the speed of performing a full code book search during vector quantization encoding.
2. Description of the Prior Art
Different techniques for vector quantization are known. Some of the methods employed require a full code book search of every vector formatted from the received image. When the number of vectors in the code book become large, and/or the vector elements become rather large or complex, the time required for a full code book search exceeds the ability of the computing system to keep pace with the input image data stream which often exceeds a rate of 10 megabits per second.
It has been suggested that a tree search of coded information would be faster than a full code book search, however, this technique produces degradation or suboptimization with a desirable increase in the speed of encoding.
It has further been suggested that hierarchical encoding could be employed to increase the speed of encoding, however, this technique also degrades the encoded results as well as being difficult to implement.
It would be desirable to be able to obtain the optimum encoded result associated with a full code book search at increased speeds without incurring the cost associated with merely purchasing greater computing power for a faster full code book search.